Electric drives for photographic enlarging and reproducing apparatus



Sept. 12, 1961 H. HAUPTVOGEL ETAL 2,999,423

ELECTRIC DRIVES FOR PHOTOGRAPHIC ENLARGING AND REPRODUCING APPARATUSFiled Sept. 6, 1957 2 Sheets-Sheet 1 HI 43 4a FIC.3

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INVENTORQJ flG/er/ 8/ BY [/1164 Sept. 12, 1961 H. HAUPTVOGEL EIAL2,999,423

ELECTRIC DRIVES FOR PHOTOGRAPHIC ENLARGING AND REPRODUCING APPARATUSFiled Sept. 6, 1957 2 Sheets-Sheet 2 FIG. 6

INVENTORE} United States Patent 2,999,423 ELECTRIC DRIVES FORPHOTOGRAPHIC EN- LARGING AND REPRODUCING APPARATUS Herbert Hauptvogeland Erich Korf, Dresden, Germany, assignors to VEB Kameraund KinowerkeDresden Filed Sept. 6, 1957, Ser. No. 682,495 Claims priority,application Germany Sept. 28, 1956 3 Claims. (Cl. 88-44) This inventionrelates to photographic enlarging and reproducing or process-workapparatus and particularly to an electromotive drive for vertical andhorizontal adjustment of the enlarging or reproducing system preferablyarranged on a common support.

The use of electromotive drives for vertical and lateral adjustments inphotographic enlarging and reproducing outfits provided with astationary driving motor disposed as a rule on or under the base plateis known. The drive required for such adjustments is transmitted by anumber of structural members, as shafts, chains, bevel gears, worms andother transmission agents with whichspindles, pull ropes, bevel gearwheels, friction rollers and the like are connected by means of whichthe units to be adjusted are finally moved. Frequently, a guide rod orcolumn has to be additionally employed.

All known arrangements of this type are open to several objections.Their manufacture is rendered uneconomical as to time, material andweight due to the various transmission members required and theiraccommodation quick reversal, particularly in case of short directionalchanges of units, so that a moved unit cannot be instantaneously startedand stopped. Owing to increased friction and the necessity of overcomingpulling and compression stresses of spindles, ropes, racks or otheradjusting means a relatively strong driving motor is needed whichincreases the total weight of the apparatus still more. The knownelectromotive drives of enlarging systems for which the drive accordingto the invention is preferably used suifer also from the drawback thatthe enlarging system cannot be turned 180 for producing large sizepictures outside the base plate without considerable structuralalteration involving large expenditures.

It is the object of the invention to provide an electromotive drivewhich eliminates these defects of the known types.

This object is attained by employing as electric drive a fractionalhorse-power motor which is not stationary but including its mechanism isdirectly attached to or mounted on the vertically or horizontallymovable support of the enlarging or reproducing system and thusparticipates in every adjusting motion of the support.

Compared with the known electromotive drives the drive according to theinvention, due to the movable arrangement of the motor, permits directtransmission of drive without the use of the numerous transmissionelements hitherto required. The manufacture is thereby considerablysimplified and production cost reduced while safety and reliability inoperation are increased. As fractional horse-power motors havepractically without exception high speed ranges, they can be greatlyreduced in simple manner so that the driving power of a fractionalhorse-power motor is entirely sufiicient for adjusting enlarging andreproducing systems whenever necessary. Furthermore, fractionalhorse-power motors can be rapidly braked and stopped and also startedwithin a short time owing to which directional changes can be exactlycontrolled even at short distance adjustments.

The fractional horse-power motor may be additionally coupled with apreferably electromagnetically acting braking device and so controlledthat the latter becomes effective as soon as the motor is switched off.The electromagnetic brake may for instance be so constructed that itnon-positively, as by spring pressure, acts on the gear when the motorhas been or is being switched off and when the motor is switched onagain is simultaneously raised out of braking position. According toanother inventive idea the electromagnetic braking device may beconstructed in such a way that it becomes effective only at the momentwhen the motor is switched off. This can be attained by activating asliding contact operating with a retarder at disengagement of the motorand during its contact action closing the circuit for theelectromagnetic braking device which is released again afterretardation. In this way, while instantaneous braking is effected whenthe motor is switched off, the electromagnetic braking device isprevented from constantly carrying current.

An electric drive formed as described reliably ensures instantaneousstoppage of the moving enlarging or reproducingsystem at the desiredadjusted position. In addition, at the end of the horizontal or verticalguide elements may be provided which automatically switch off theelectric drive when these end positions are reached whereby also seizingand gear troubles connected therewith are avoided at these positions.

The employment of fractional horse-power motors affords also theadvantage of a corresponding reduction of the total weight of theapparatus, and the drive according to the invention permits furthermoreto turn the enlarging or reproducing system One embodiment of theinvention applied to a photographic enlarging unit is illustrated in theaccompanying drawings, wherein FiGURE 1 is a diagrammatic layout of thedrive of an enlarging unit;

FIG. 2 shows an example of an electromagnetic braking device using abrake magnet;

FIG. 3, a corresponding wiring diagram;

FIGS. 4 and 5 show an example of construction of an electromagneticbraking device with a lifting magnet; and

FIG. 6 shows a corresponding wiring diagram.

The diagrammatic layout shown in FIG. 1 comprises a fractionalhorse-power motor 1, a reduction system 2 suitably consisting of a wormand worm wheel, a driving wheel 3, a rack 4 for driving wheel 3, a motorbrake disk 5, a motor brake 6, an upper cut-out 7, a lower cut-out 8, anupper control pin 9 for cut-out 7, a lower control pin 10 for cut-out 8,a support 11 of the enlarging system with which the gear is connected,12 is one of the two push-button switches disposed on the front surfaceof the base plate 13, and 14 is the guide column of the enlargingoutfit.

The mode of operation is as follows:

When one or the other switch 12 is operated, the fractional horse-powermotor 1 provided on the support 11 of the enlarging system commences toT1111 and over driving gear 2, 3 and rack 4 moves the support 11 withthe enlarging system along the guide column 14 up or down in verticaldirection depending on which one of the two switches 12 has beenactuated. Before the uppermost adjustment has been reached, the controlpin 9 strikes against the cut-out 7 and, inversely, control pin 10strikes against cut-out 8 before the lowest end position has beenreached. In these end positions the current is switched off by thecut-outs 7, 8 so that sticking of the support 11 in these positions isnot possible.

When the electric drive is switched off in these or in other adjustedpositions, the fractional horse-power motor 1 is simultaneously brakedif the drive is fitted with an electromagnetic braking device accordingto FIGS. 2-6, which operates as follows:

With respect to the braking device shown in FIGS. 2 and 3 braking isefiected by the electromagnet 6 Whose core is pressed by spring actionupon the motor disk 5, and this braking e'ltect continues until thecircuit is intermpted or the motor switched off. During switching on ofthe motor the electromagnet 6 receives simultaneously current andthereby moves the brake core out of braking position against thepressure of the spring.

In the braking arrangement accordingto FIGS. 4-6 the circuit of theelectromagnet 6 remains interrupted as long as the motor runs. When thelatter is switched off, the slide contact 15 connected withelectromagnet 6 is activated, whereby the motor disk is braked via thecore of the magnet. The duration of this braking effect is delayed by aretarding device 16 in engagement with switch 12 until at the returnmotion of switoh'12 the slide contact is interrupted again.

Compared with known drives, the drive according to the invention isdistinguished by its rapid and unfailing reaction to an adjustment madeby simple pushbutton switches and to a reversal of motion of a unit inboth directions even over shortest distances.

We claim:

11. An enlarging apparatus comprising a stationary base plate, a guidingcolumn supported by and substantially perpendicular to said base plate,a rack attached to and extending along the major portion of said guidingcolumn,

a movable carriage member on said guiding column along which it can bereciprocated, an optical projection unit on said carriage member,electric drive means secured to said carriage member, a gear driven bysaiddrive means and engaging said rack for reciprocating said carriagemember, a source of electric power, control means for enengizing saiddrive means from said source of power, and limit switch means comprisinga cut-out switch attached adjacent each end of said rack and an abutmentat either side of said carriage member, said abutments being adapted tooperate said cut-out switches in the extreme positions of said carriagemember so as to de-ener- 4 gize said drive means to bring said carriagemember to a stop.

2. An enlarging apparatus, according to claim 1 wherein said guidingcolumn can be swiveled by about degrees along its axis together withsaid carriage member, said electric drive means and said opticalprojection unit movable thereon.

3. An enlarging apparatus comprising a stationary base plate, a guidingcolumn supported by and substantially perpendicular to said base plate,a rack attached to said guiding column, a movable carriage memberreciprocable along said guiding column, an optical projection unit onsaid carriage member, electric drive means secured to said carriagemember and engaging said rack for reciproeating said carriage memberwith respect to said rack, electromagnetic brake means on said carriagemember for normally impeding the movement of said drive means whende-energized and when energized allowing free movement of said drivemeans, a source of electric power,

and control means for simultaneously energizing said drive means andsaid brake means from said source of power, said brake means engagingsaid drive means only in its de-energized condition.

References Cited in the file of this patent UNITED STATES PATENTS1,176,691 Ricker et a1. Mar. 21, 1916 2,153,186 Henderson Apr. 14, 19392,194,384 Dewey Mar. 19, 1940 2,377,286 White May 29, 1945 2,424,385Cook July 22, 1947 2,465,692 Martinsson Mar. 29, 1949 2,492,898Siekermann Dec. 27, 1949 2,607,265 Petrucelli Aug. 19, 1952 72,655,834Pennington Oct. 20, 1953 2,859,331 Grimes Nov. 4, 1958 FOREIGN PATENTS578,393 Great Britain June 26, 1946 860,453 Germany Dec. 22, 1952

